Method of producing lined concrete pipe



Nov. 9, 1965 H. cocKE METHOD OF PRODUCING LINED CONCRETE PIPE Filed Feb. 27, 1962 iiiiiiiiiiiiiii.

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BY @Zvw 9 afk/WW Hmm United States Patent M 3,217,077 IVIETHOD F PRODUCING LINED CONCRETE PIPE Hill Cocke, P.0. B0X 1751, Harlingen, Tex. Filed Feb. 27, 1962, Ser. No. 175,972 4 Claims. (Cl. 264-256) This invention relates to a method of producing plastic lined pipe and is a continuation-in-part of copending application U. S. Serial No. 843,839, tiled October 1, 1959, now abandoned.

An object of the invention is to provide a method for producing protectively lined pipe sections having a coating of material such as fiberglass or other resinous substances that will provide an impervious barrier to deterioration attributable to liquids and gases conducted through the pipe sections.

More particularly, the invention provides a method for producing precast concrete pipe sections completely lined with a synthetic resinous substance which will bond to concrete and will be impervious to liquids and gases rendering said pipe sections particularly useful in sewer lines.

The procedure of the present invention involves therefore, the spraying or otherwise depositing of a plastic substance while it is in a uent state about a reducible form and to a thickness of approximately one-eighth of an inch. Before the uent plastic hardens, to expose a nonporous surface, concrete is cast thereabout to form a tubular body which becomes bonded to the plastic lining as both the concrete and the plastic set. Similarly, an outer plastic lining is bonded to the tubular concrete body by deposit thereof prior to complete setting of the concrete. Plastic linings with the exposed acid-proof surfaces have heretofore been applied to concrete surfaces in the formation of composite concrete conduit sections, but have used different, more difficult and costly methods to obtain adhesion of the lining to the concrete surface. For example, the plastic substance such as asphalt in an adhesive state, had been applied firstly to a exible sheet or paper to which it becomes bonded before being applied to the concrete surface as in the case of the method disclosed in Patent Nos. 1,387,065 and 2,321,277 in which case the paper either remained or the plastic surface exposed by removal of the paper through wetting. Also, adhesion of the plastic to the concrete depended on embedment of either reinforcing elements or sand in the concrete. In sharp distinction thereto, the method of the present invention relies on simultaneous setting of both the concrete and the plastic brought into contact when both are in the adhesive state. In this way, bonding is achieved without use of supporting sheets requiring removal in order to expose the acid-proof surface of the plastic and without use of elements embedded between the concrete and the plastic.

In one embodiment of the invention, metal reinforcement is embedded both in the plastic lining and the concrete. The reinforcement will thus provide a mechanical anchor for both the plastic and the concrete to achieve better adherence for bonding purposes as well as to improve the plastic and concrete in strength when the material has set.

The composite pipe section formed as a result of the foregoing method, will be desirable for sanitary sewer lines despite the manufacture thereof utilizing concrete 3,217,077 Patented Nov. 9, 1965 which has heretofore been avoided since ordinary concrete pipe sections deteriorate rather rapidly in response to attack by sewer gases.

In accordance with the foregoing objects, an important feature of the invention resides in the joints of the composite pipe sections. The pipe sections aretherefore so constructed that when axially assembled with each other the joints will set tight without bonding of the contacting plastic material or lining as was required in the prior art. Instead, a concrete backed sealing surface of plastic material in one pipe section cooperates with an elastically deformable plastic sealing portion axially projecting from an adjacent pipe section seating an O-ring to form a sealing gasket effective to prevent leakage of liquids or gases yet permitting a certain degree of radial displacement between adjacent interfitted pipe sections.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

FIGURES 1 through 5 illustrate the various steps in the manufacture of the composite pipe sections of the present invention.

FIGURE 6 is a perspective view of a typical pipe section made in accordance with the novel method of the present invention.

FIGURE 7 is an enlarged partial sectional View illustrating the joints between adjacent composite pipe sections.

Referring now to the drawings in detail, it will be observed from FIGURES 6 and 7, that the composite pipe section generally referred to by reference numeral 10 includes a tubular body of concrete 12 within which reinforcing wire 14 is embedded wound about a plurality of circumferentially spaced guide rods 16 forming a reinforcing assembly for the concrete material. The tubular concrete body 12 is internally recessed at one axial end thereof to form a rigid backing 18 for a sealing surface portion 20 of plastic material completely coating the concrete tubular body 12 including an inner lining portion 22 interconnected by the sealing surface portion 20 of the material to an outer plastic lining 24. An annular sealing portion 26 formed of the same plastic material extends axially from the inner lining portion 22 at the end of the tubular concrete body 12 opposite the portion 18 thereof. The sealing portion 26 is therefore connected by plastic material to the outer lining portion 24 so as to completely coat the tubular concrete body 12. An annular recess 28 is formed in the sealing portion so as to receive an O-ring element 30 for sealing contact with the sealing surface portion 20 of the plastic material of an adjacent concrete section intertted therewith. In order to render the sealing portion 26 elastically deformable in order to properly respond to internal pressure of sewer gas and permit assembly of the concrete sections, inner reinforcing wire 32 is embedded in the sealing portion 26. The inner reinforcing wire 32 may optionally be extended in an axial direction so as to reinforce the entire inner plastic lining portion 22. As a further optional feature, outer reinforcing Wire 34 may be wound about the concrete tubular body and embedded within the outer plastic lining portion 24 so as to impart additional strength thereto.

The composite concrete pipe section 10 as hereinbefore described, takes advantage of the strength and manufacturing economy associated with reinforced concrete. The plastic lining furthermore renders the concrete pipe section suitable for sewer line use and also by virtue of a novel arrangement with respect to the concrete body, facilitates assembly of the pipe sections and sealing therebetween. Furthermore, the composite pipe sections are particularly useful because of the novel method of producing said sections to be described hereafter.

Referring now to FIGURES 1 through 5, it will be observed that the initial step in the method of manufacture involves the placement of the inner reinforcement wire 32 about the shank portion 36 of a reducible type of form 38 also having a base portion 40 arranged to form the recessed socket portion at one axial end of the pipe section. The base portion 40 is set upon the bottom plate portion 42. The base portion 40 includes a slightly beveled section 44 arranged to form the entrance portion of the annular socket recess at one axial end of the composite pipe section. Also, the inner reinforcing wire 32 wound about the shank portion 36, may be restricted to an upper section thereof if it is desired to reinforce only the sealing portion 26 of the composite pipe section. Accordingly, the next step in the manufacturing method, as illustrated in FIGURE 2, is to apply a coating of the plastic material which is some form of synthetic resinous substance in order to form the inner lining portion 22 about the shank portion of the form 38 and the sealing surface portion 20 about the base portion 40. Synthetic resinous substances in a fluent state which are settable under ambient temperature conditions and having the aforementioned sealing and chemical resistant properties are well known such as the organo polysiloxanes or silicone-rubber compounds and including products such as Silastic manufactured by the Dow Chemical Corporation. It should of course be appreciated that the particular composition of the synthetic resinous substances utilized form no part of the present invention since various materials having the indicated properties are well known to those skilled in the art and are available for use in accordance with the present invention. The plastic coating applied to the form 28 may be accomplished in several different ways including for example dipping or spraying. The next step as illustrated in FIGURE 3, involves the assemblage of the concrete reinforcement in encircling relation about the shank and base portions of the form 38 in radially spaced relation to the plastic coating thereon. Accordingly, the circumferentially spaced guide rods 16 are placed above the lower radially annular portion 46 of the plastic lining disposed on the plate member 42 and the reinforcing wire 14 wound thereabout. The upper section 4S of the plastic lining portion 22 is however left exposed. The next step therefore involves the casting of the tubular concrete body 12 including the portion 18 thereof about the form 38 while the plastic coating is still in a tacky condition so that bonding will occur between the concrete and the inner plastic lining. After the concrete has been so cast, the sealing portion 26 of plastic material may be applied to the exposed portion 48 of the inner lining 22 either by some molding process or by building up the thickness of the exposed inner lining portion 48 through additional spraying of plastic material. Optionally, an outer reinforcing wire 34 may then be wound about the concrete tubular body 12 as shown in FIGURE 4, so that completion of the manufacture of the concrete sections may be accomplished by coating the remaining exposed surfaces of the tubular concrete body 12 to form the outer lining portion 24 embedding the outer reinforcing wire 34 if used; see FIGURE 5. After all of the materials` have completely set or hardened, the form 38 may be removed.

From the foregoing description, it will be appreciated that a superior conduit section is produced wherein the reinforcement utilized, which may be f any suitable type, not only cooperates to improve the strength of the section but also insures adherence of the concrete with the plastic while in a tacky state or before complete setting so that when setting has been completed, a good bond between the plasic and concrete will have been formed. The resulting pipe sections will therefore have the advantages of all reinforced concrete sections and yet be suitable for sewer line use because of the facilitated sealing between concrete sections and the protection against liquids and gases that the non-porous plastic material provides. The direct application of the plastic material to the core and casting of the concrete in contact with the plastic while in an adhesive state, will produce the bonding of the lining to the concrete surfaces by simultaneous setting of the concrete and plastic and thereby eliminate the need for elements extending between the contacting surfaces and separately embedded in the concrete and plastic. Also eliminated is the use of flexible sheets bearing the plastic when brought into contact with the concrete avoiding the steps necessary for removal of the sheet to expose the non-porous surface of the plastic after setting.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modiications and equivalents may be resorted to, falling within the scope of the invention as claimed.

What is claimed as new is as follows:

1. A method of producing protectively lined concrete pipe section comprising the steps of: placing inner reinforcement about a shank portion of a form having a base portion; coating the base portion and shank portion of the form with a plastic resinous material which is settable and bonds with concrete for embedding the inner reinforcement therein to form an inner lining which is non-porous; placing reinforcement in encircling relation to the base portion and shank portion of the form radially spaced from the inner lining leaving exposed a section thereof; casting concrete about said encircling reinforcement while the material of said inner lining is tacky for bonding thereto; applying said resinous material about said exposed section of inner lining to form a sealing portion therewith; placing outer reinforcement about said cast concrete; coating exposed surfaces of said cast concrete with said resinous material before complete setting of the concrete to form an outer lining bonded thereto and embedding said outer reinforcement, and withdrawing said form after setting of the plastic to expose a non-porous surface of the lining.

2. The method of claim 1, wherein placement of said inner reinforcement is restricted to said exposed section of the inner lining.

3. A method of producing protectively lined concrete pipe section comprising the steps of: placing inner reinforcement about a shank portion of a form having a base portion; coating the base portion and shank portion of the form with a synthetic resin plastic which is settable and bonds with concrete for embedding the inner reinforcement therein to form an inner lining which is nonporous; placing reinforcement in encircling relation to the base portion and shank portion of the form radially spaced from the inner lining leaving exposed a section thereof; casting concrete about said encircling reinforcement while the plastic of said inner lining is tacky for bonding thereto; applying said plastic about said exposed section of inner lining to form a sealing portion therewith; coating exposed surfaces of said cast concrete with said plastic before complete setting of the concrete to form an outer lining bonded thereto, and withdrawing said form after setting of the plastic to expose a non-y porous surface of the lining.

4. The method of claim 3, wherein placement of said lnner reinforcement is restricted to said exposed section of the inner lining.

References Cited by the Examiner UNITED STATES PATENTS Murray 264-279 Tuerck.

Ligonnet 264-270 nlemann 264-270 10 Esehenbrenner 285-55 Chappell.

Carson 264-270 Boyle 25-38 Ferla 285-55 Serken 264-256 Munger. Goldfein 264-228 Sergovic 13S-141 FOREIGN PATENTS Great Britain. Great Britain. Norway.

ROBERT F. WHITE, Primary Examiner.

CARL W. TOMLIN, Examiner. 

1. A METHOD OF PRODUCING PROTECTIVELY LINED CONCRETE PIPE SECTION COMPRISING THE STEPS OF: PLACING INNER REINFORCEMENT ABOUT A SHANK PORTION OF A FORM HAVING A BASE PORTION; COATING THE BASE PORTION AND SHANK PORTION OF THE FORM WITH A PLASTIC RESINOUS MATERIAL WHICH IS SETTABLE AND BONDS WITH CONCRETE FOR EMBEDDING THE INNER REINFORCEMENT THEREIN TO FORM AN INNER LINING WHICH IS NON-POROUS; PLACING REINFORCEMENT IN ENCIRCLING RELATION TO THE BASE PORTION AND SHANK PORTION OF THE FORM RADIALLY SPACED FROM THE INNER LINING LEAVING EXPOSED A SECTION THEREOF; CASTING CONCRETE ABOUT SAID ENCIRCLING REINFORCEMENT WHILE THE MATERIAL OF SAID INNER LINING IS TACKY FOR BONDING THERETO; APPLYING SAID RESINOUS MATERIAL ABOUT SAID EXPOSED SECTION OF INNER LINING TO FORM A SEALING PORTION THEREWITH; PLACING OUTER REINFORCEMENT ABOUT SAID CAST CONCRETE; COATING EXPOSED SURFACES OF SAID CAST CONCRETE WITH SAID RESINOUS MATERIAL BEFORE COMPLETE SETTING OF THE CONCRETE TO FORM AN OUTER LINING BONDED THERETO AND EMBEDDING SAID OUTER REINFORCEMENT, AND WITHDRAWING SAID FORM AFTER SETTING OF THE PLASTIC TO EXPOSE A NON-POROUS SURFACE OF THE LINING. 